The present invention relates to a process for decolorizing polyethylene polyamines and, more particularly, to a process for producing polyethylene polyamines having improved color characteristics by treatment with hydrochloric acid which may be run continuously.
It is well known that polyethylene polyamines, and particularly the higher polyamines, become discolored during their preparation which generally reduces their commercial value. Heretofore, various procedures have been used commercially or suggested for decolorizing or otherwise improving the color of these compounds including, for example, treating with hydrogen chloride or amine hydrochlorides as disclosed in U.K. Pat. No: 1,351,050; treatment with activated carbon at elevated temperatures (about 200.degree. C.); treatment with potassium hydroxide; and treatment with zinc metal, zinc metal and water, or zinc metal and an alkali. In each of these procedures, distillation is generally a final step needed to achieve the desired color, and neutralization of residues, handling and separation of metal powders, or reactivation of the treatment medium require special apparatus which complicate the process. Moreover, to the best of our knowledge none of these procedures are completely suitable for the continuous preparation of decolorized polyamines.
It would, thus, be highly desirable if a process was developed which was generally simple but could be employed to decolorize various polyamines, and particularly the higher polyamines, to obtain color levels of 100 Platinum-Cobalt or less, that did not require special or complicated apparatus and/or procedures, and did not involve the handling or disposal of treating materials. A process that could be used to continuously prepare decolorized polyamines would be particularly advantageous.